The final result was a lot neater, but was slow to produce and very stringy. I went in and made some changes, increasing the speed and de-selecting the "use firmware retraction" checkbox that had been set previously for some reason. The result is quite decent, I think.

The top fill on the 4 corner steps isn't as nice as I'd like, being quite rough and messy. However, it's a big step forward from previous results.

I'm still having a few problems: I'm having all sorts of issues with calibrating the extruder, getting different results every time I try. Also, my 1.75mm E3Dv6 hot-end jammed up AGAIN, which is a real pain - I have a 3mm E3Dv6 on my Prusa, and I think I've had 1 jam since I fitted it, and that was only because the cooling fan failed and the heat got up into the body. I'm not sure I like working with 1.75mm filament...

Quotedougal1957ooznest do the Delrin Openbuilds mini V-Wheels and ship out same day if in stock they also do V Slot extrusion at a fair price (Tho not as cheap as Motedis)

Oh thank you! I saw ooznest before on ebay but never checked out their online store where they are much cheaper than on ebay. About ~20% markup compared to openbuilds incl vat. 43.39 € for 9 mini v wheels including shipping. Well still expensive but YOBO right? (you only build once)

Quotedougal1957ooznest do the Delrin Openbuilds mini V-Wheels and ship out same day if in stock they also do V Slot extrusion at a fair price (Tho not as cheap as Motedis)

Oh thank you! I saw ooznest before on ebay but never checked out their online store where they are much cheaper than on ebay. About ~20% markup compared to openbuilds incl vat. 43.39 € for 9 mini v wheels including shipping. Well still expensive but YOBO right? (you only build once)

YOBO I only wish that was true the mistakes I have made along the way.

My build actually uses 12 wheels 4 on each carriage with 2 on each being on eccentric spacer's to allow for tension adjustment (I think this makes a more solid carriage arrangement and has less Backlash in it) I am also using the Robotdigg Alloy Kossel Parts on mine as well and they make a huge difference in the solidity of the frame Robotdigg Alloy delta parts

If you want the Cad files I can post them as well and if you say what format you'd like I can try and export them (I Use Freecad).

Sorry bout the focus on the first 2 but you should get the idea the second one shows the Hexagonal Eccentric Spacer's (1/4 inch ones to replace the standard ones) and I have used the OpenBuilds V-Slot extrusion).

I'm not a huge fan of this design in general, as the OpenBuilds plate and eccentrics will not provide me with enough adjustment range to take all of the slop out of the wheels on their V-slot extrusions.

I'm not a huge fan of this design in general, as the OpenBuilds plate and eccentrics will not provide me with enough adjustment range to take all of the slop out of the wheels on their V-slot extrusions.

The reason I didn't use them is the hole pattern on them (For mounting the Rod Carrier's) was not quite right (I could have got them to fit but would only of used 2 holes and ofset from the joint centres which I didn't want) hence I took the openbuild design and extended the height by 10 mm and put my own bolt pattern in for the carriers.

I find that there is plenty of adjustment in them for the Openbuilds V-Slot rails which is after all what they are designed for.

I have managed to get them set up with no descernable backlash in fact I may have them a little to tight.

Dejay ooznest have engineering drawing's of the plates on there website.

The reason I didn't use them is the hole pattern on them (For mounting the Rod Carrier's) was not quite right (I could have got them to fit but would only of used 2 holes and ofset from the joint centres which I didn't want) hence I took the openbuild design and extended the height by 10 mm and put my own bolt pattern in for the carriers.

I find that there is plenty of adjustment in them for the Openbuilds V-Slot rails which is after all what they are designed for.

You can see in the picture above what I wound up doing. I drilled two holes from the back, and used a pair of low-profile SHCS to attach the plate. (The screws are also black, and coincidentally wound up with the tips being flush with the printed rod mount if you look inside the belt holder and the dimple in the big open space.)

When I ordered the set from OpenBuilds (1.5 years ago), they recommended two eccentrics and two standoffs for the four wheels. When I crank the eccentrics all the way in, I am *barely* getting a play-free carriage on their V-slot. Maybe they adjusted the plate or are recommending 4 eccentrics now, but the parts that I received were marginally usable. Plus, I don't think that they ever considered the off-center carriage shift of a few millimeters when using the eccentrics. I'm still planning to use them on my spin of the HotBot2 (as pictured), but will probably replace them with a new design as soon as I can use it to print ABS without warping.....

The reason I didn't use them is the hole pattern on them (For mounting the Rod Carrier's) was not quite right (I could have got them to fit but would only of used 2 holes and ofset from the joint centres which I didn't want) hence I took the openbuild design and extended the height by 10 mm and put my own bolt pattern in for the carriers.

I find that there is plenty of adjustment in them for the Openbuilds V-Slot rails which is after all what they are designed for.

You can see in the picture above what I wound up doing. I drilled two holes from the back, and used a pair of low-profile SHCS to attach the plate. (The screws are also black, and coincidentally wound up with the tips being flush with the printed rod mount if you look inside the belt holder and the dimple in the big open space.)

When I ordered the set from OpenBuilds (1.5 years ago), they recommended two eccentrics and two standoffs for the four wheels. When I crank the eccentrics all the way in, I am *barely* getting a play-free carriage on their V-slot. Maybe they adjusted the plate or are recommending 4 eccentrics now, but the parts that I received were marginally usable. Plus, I don't think that they ever considered the off-center carriage shift of a few millimeters when using the eccentrics. I'm still planning to use them on my spin of the HotBot2 (as pictured), but will probably replace them with a new design as soon as I can use it to print ABS without warping.....

I think that they did consider the offset carriage and dimensioned everything from the non Eccentric holes see Mini Vee Wheel carriages Drawing (Openbuildpartstore done seem to have this published) and it is this drawing I used to do my own and altered the vertical spacing of the wheels by I think 10 mm which helps to run a little truer as well must admit that mine are also close to the limit of adjust ment and maybe reducing the width between centres of the holes from 31.9 to something more like 31.5 may have been better.

I printed mine in ABS and made them 10 mm thick.

Printer seems to be doing ok at the moment still a little bit of fine tuning to do but I am printing at 100 mm/s at the moment next job will be an enclosure for ABS Printing.

A good rule of thumb is that the rods should be at 30 degrees to the vertical when the effector is centred, which means the rod lengths are twice the delta radius. Slightly shorter is OK, e.g. I have 300mm printable diameter, 180mm delta radius, and 350mm rods.

This is the length of the arms when they are at the end of the 220mm bed, and the arms are 90 degrees with the tower, which I don't think is good.

Adding 9% to the arms will give me:
Arms length: 294mm
Degrees between arms and tower: 32.91
Lost height: 236.92

For 300mm printable diameter my calculation gave 337mm rods, so I did the right calculations.

Thank you!

Doing the sums for my printer, the angle of the rods to the vertical works out as 31 degrees. So your 32.9 degrees is still a little high compared to my build, and you might want to make the arms a little longer still.

A few useful formulae:

Delta radius = horizontal distance spanned by each of the 6 arms when the effector is in the centre of the bed

Print radius = delta radius - horizontal distance spanned by a pair of rods to the closest tower when the effector is as close to the tower as it can get

Therefore, if the geometry allowed the rods to become vertical when the effector is close to a tower, you would have print radius = delta radius. In practice, the effector can''t usually get that close, so the print radius is less then the delta radius (by 30mm in my build). If the arms are long enough and the joints have enough movement, you may be able to print out to more than the "print radius" as I have defined it above when the effector is between the nearest towers.

I have just put a duet controller into my Cherry Pi and I am having a strange issue. If I move the motors, everything moves okay but once the motor stops at the correct place it is still making a noise for 10+ seconds after. If I hit the emergency stop the noise stops. I have taken a video of it here:-

I have the motor ratings in the config.g file set to 1700, which is what the stepper motors are supposedly rated for, but setting this at 1000 doesn't appear to make a difference to the noise after move.

Thanks

Matt

Edit:

Reading around about stepper motors and I think I understand. The noise when the motor is not moving is because you have to keep the stepper energised to stop in moving. I never heard this on the ramps, but I guess the voltage to hold the motor was different in the drivers I had on the ramps.

I have just put a duet controller into my Cherry Pi and I am having a strange issue. If I move the motors, everything moves okay but once the motor stops at the correct place it is still making a noise for 10+ seconds after. If I hit the emergency stop the noise stops. I have taken a video of it here:-

I have the motor ratings in the config.g file set to 1700, which is what the stepper motors are supposedly rated for, but setting this at 1000 doesn't appear to make a difference to the noise after move.

Thanks

Matt

Edit:

Reading around about stepper motors and I think I understand. The noise when the motor is not moving is because you have to keep the stepper energised to stop in moving. I never heard this on the ramps, but I guess the voltage to hold the motor was different in the drivers I had on the ramps.

Hi Matt,

Running the motors at their rated current is not necessary and not a good idea. Both the motors and the drivers will get hot. If the motors are 48mm long Nema 17s like mine (which are also rated at 1.7A), then 800mA is probably enough (I use just 500mA for my extruder motor). If they are shorter, you may need 1000mA to 1200mA. Your RAMPS drivers will have been set much lower than 1.7A - if you know what voltage you had them adjusted to, you can work it out.

After editing new values into the M906 command in config.g and uploading it, you need to restart the machine to make it read config.g again. The easiest way to do this is to use the Emergency Stop button on the web interface. You can also adjust current on the fly sending the M906 command to the printer. Sending M906 with no parameters causes the existing values to be echoes back.

The reason it goes quieter after a while is that after 30 seconds of inactivity, the firmware reduces the current to the idle hold value. By default, this is 30% of the normal current. You can adjust it using the I parameter in the M906 command, e.g. M906 I50 will make the idle hold current 50% of the normal current.

Edit, it actually looks like the calibration isn't running fully. It only probes all the points once then homes, which I thought might mean its finished, however I just had it probe all the points twice then just stop and not home.